Description
Alloy 20 Round Bar
Alloy 20 Round Bar is a Nickel Iron Chromium based, austenitic alloy with excellent corrosion resistance in chemical environments containing sulfuric acid and many other aggressive media. This alloy is stabilized with niobium to resist intergranular corrosion. Alloy 20 may provide potential cost savings when carefully compared to higher nickel-based alloys, while out performing standard stainless steels.
Alloy 20 is a nickel-iron-chromium austenitic alloy developed with the additions of copper and molybdenum for maximum resistance to acid attack, specifically sulphuric acid.
It has excellent resistance to generation corrosion, pitting and crevice corrosion in chemicals containing chlorides, sulphuric, phosphoric and nitric acids. This means it offers strong resistance to chloride stress corrosion cracking.
It also contains niobium for stabilization against sensitization and resultant intergranular corrosion. It excels in resisting corrosion to hot sulphuric acids.
Alloy 20 combines excellent corrosion resistance with elevated mechanical properties and relatively easy fabrication. Its stabilization also minimizes carbide precipitation during welding.
While it was originally designed for use in sulphuric acid related industries, Alloy 20 is now a popular choice in a variety of industries including the chemical, food, dye, pharmaceutical and plastics industries. In addition, this superalloy is used in heat exchangers, mixing tanks, metal cleaning and pickling equipment and piping.
The nickel content of Alloy 20 is on the border between a nickel alloy and stainless steel. It may also be referred to as alloy 20 stainless steel.
Alloy 20 Chemical Composition of Alloy 20 :
| Elements | Min. – Max. % |
| (Fe) Iron | Remainder |
| (Ni) Nickel | 32.00 to 38.00 |
| (Cr) Chromium | 19.00 to 21.00 |
| (Cu) Copper | 3.00 to 4.00 |
| (Mo) Molybdenum | 2.00 to 3.00 |
| (Mn) Manganese | 2.00 max |
| (Nb+Ta) Niobium* + Tantalum | (8 x C) to 1.00 |
| (Si) Silicon | 1.00 max |
| (C) Carbon | 0.07 max |
| (P) Phosphorus | 0.045 max |
| (S) Sulfur | 0.035 max |
*Niobium (Nb) formerly classified as Columbium (Cb).
Resistance to Corrosion of Alloy 20 :
Alloy 20 / W.Nr. 2.4660 has very good resistance to sulfuric acid. This alloy also shows suitable resistance in phosphoric acid, nitric acid and aqueous salt solutions. Alloy 20 is an excellent option when chloride stress corrosion cracking is an issue, as it resists pitting and crevice corrosion. Caution should be taken in chloride ion containing environments because the corrosion rate can increase significantly.
Applications of Alloy 20 / UNS N08020 / W.Nr. 2.4660 Round Bars :
Alloy 20 (UNS N08020) is used in a variety of industries, including chemical processing, petrochemical and refining, marine, pharmaceutical and food processing. End use applications include storage tanks, mixing tanks, agitators, pump and valve parts, food processing equipment, fasteners and fittings. Applications are limited to a maximum temperature of 1000°F per ASME. It is also important to determine if the necessary corrosion resistance can be achieved within the given environment.
Synthetic rubber manufacturing equipment
Processing of pharmaceuticals, plastics and organic and heavy chemicals
Tanks, piping, heat exchangers, pumps, valves, and other process equipment
Acid cleaning and pickling equipment
Chemical process piping, reactor vessels
Bubble caps
Petrochemical process equipment
Food and dye production
Sulfuric acid pickling tanks, racks and heating coils
Phosphate coating drums and racks
Heat exchangers
Process piping
Mixing tanks
Chemical and petroleum process equipment
Common Trade Names :
INCOLOY® alloy 20, Carpenter® 20 alloy, 20CB-3®
INCOLOY® is a registered trademark of the Special Metals Corporation group of companies.
Carpenter® and 20CB-3® are registered trademarks of Carpenter.
UNS N08020
DIN 2.4660
CN7M
Carpenter 20CB-3
AL 20
Carlson Alloy C20
Nickelvac 23
Nicrofer 3620Nb
VDM Alloy 20
Incoloy Alloy 20
Applicable Specifications of Alloy 20 Grade :
| Form | ASTM | ASME |
| Bar | B473 | SB473 |
| Sheet & Plate | B463 | SB463 |
| Seamless Pipe & Tube | B729 | SB729 |
| Welded Pipe | B464, B474* | SB464, SB474 |
| Welded Tube | B468 | SB468 |
*Electric fusion welded pipe material only.
Features of Alloy 20 :
Excellent resistance to hot sulfuric acid
Resistant to intergranular corrosion in the as-welded condition
Chloride stress corrosion cracking resistance